Inhaling Apparatus

ABSTRACT

An inhaling apparatus is to be used by a user to inhale a liquid medical agent from an inhalation port thereof. It has a liquid medical agent ejecting section having an ejection port for ejecting a liquid medical agent as droplets and a pressure detecting section for detecting the negative pressure produced by the atmospheric pressure as pressure difference at the time of inhalation of the user for the purpose of controlling the ejection of droplets from the ejection port. The ejection port of the liquid medical agent ejecting section is arranged at a position adapted to produce a pressure difference smaller than the pressure difference with the atmospheric pressure as detected by the pressure detecting section at the time of the inhaling action of the user.

TECHNICAL FIELD

This invention relates to an inhaling apparatus. More particularly, itrelates to an inhaling apparatus for ejecting droplets of a medicalagent, an aromatic, nicotine or some other savory substance and causesthe user to inhale them.

BACKGROUND ART

Our society is aging because of the prolonged mean life that is realizedby the advancement of medicine and science in recent years. On the otherhand, new diseases and infectious diseases have been found due to thechanges in the living environment and the eating habits, theenvironmental pollution and new strains of viruses and microbes to makepeople anxious about their health. Particularly, in the so-calledadvanced countries, the increasing number of medical patients sufferingfrom life-style related diseases, including diabetes and hypertensionimposes a serious problem on the society.

For example, diabetic patients have to be dosed with insulin.Conventionally, it is a general practice to inject insulin to a diabeticpatient after each meal. Dosing insulin by means of a syringe forcespain on the part of the patient. To solve this problem, dosing amedicine by way of the respiratory system of the patient has beendiscussed. Generally three techniques of dosing a medicine are known todate. They include the use of a metered dose inhaler, the use of a drypowder inhaler and the use of an atomizer.

Metered does inhalers (MDIs) are being widely used to treat asthma. AnMDI is provided with a valve for ejecting a dose of aerosol inoperation. The apparatus main body can be downsized for the convenienceof portability, although each dose can vary to a considerable extent.Additionally, the user of an MDI is required to operate the valve andinhale the dose in a considerably synchronized manner. and many usersfeels the synchronized operation of the MDI difficult and cumbersome.

The user of a dry powder inhaler (DPI) is required to inhale a largevolume of air in order to effectively apply dry powder to the inside ofthe bronchus system of the user with a sufficient degree of fluidity.While dry powder inhalers may be free from the above-described problemof synchronizing the valve operation and the inhalation of the dose, itis a considerable burden for the user of a dry powder inhaler to inhalea large volume of air. Additionally, patients who are sensitive tomoisture and also to the inhaled powder cannot use a DPI because thepatient can burst into a fit of asthma. Additionally, since the powerfor inhaling air varies from person to person, the dose can vary alsofrom person to person.

An atomizer is adapted to generate aerosol by atomizing liquid by meansof a carrier gas flow. It requires a gas compressor that operatescontinuously or a large volume of compressed gas for its operation.Generally, the size of aerosol droplets is a function of the pressureand the velocity of carrier gas and hence it is not easy toindependently change the concentration of the medical agent, in a gasflow. Additionally, as the patient inhales the atomized liquid, thepressure in the nozzle of the atomizer falls. In other words, the doseand the particle size of the medical agent are affected by the periodand the strength of each breathing action.

Thus, the above-described known apparatus are accompanied by the problemof a low degree of precision of applying a right dose of a medical agentof right particle size to a right position of the patient body. In otherwords, they can be used only for medical agents that show a largetolerance in terms of dose. In any case, currently, it simply relies onthe technique of the user for applying a right dose to a right position.

On the other hand, there is a demand for improved medicinaladministration systems that can be used to optimally cure diseases ofthe nose and those of the lung by means of a medical agent that worksonly locally. Additionally, it has been proved as a result of theadvancement of medicine in recent years that application of a medicalagent such as protein, peptide or an analgesic to the lungs isadvantageous if compared with conventional administration techniquessuch as oral administration and injection. However, known inhalerscannot be used for such applications because they are accompanied by theproblem of variable particle size and that of variable dose.

These problems will be described in greater detail by way of examples.Of the current diabetic patients, whose number is increasing, thosesuffering from insulin dependent diabetes mellitus, which is alsoreferred to as type I diabetes mellitus, do not secrete insulin from thepancreas and hence insulin has to be administered periodically to them.

Currently, administration of insulin is realized by means ofsubcutaneous injection to impose a great physical and mental burden onthe patient. Pen-type syringes designed to use a very thin needle havebeen developed to significantly reduce the pain on the part of thepatient. However, many patients suffering from type I diabetes mellitusare working like healthy people unless insulin has to be administeredperiodically to them and it will be mentally difficult for such apatient to inject insulin to him- or herself by means of a syringe whilehe or she is exposed to the public if the syringe is of the pen-type.

Thus, there is a demand for an easy method of administering a medicalagent by the patient him- or herself that does not involve the use of asyringe but can eject the medical agent in the form of droplets anddrive them to reliably reach the lungs.

Recently, there have been proposed methods for ejecting aphysiologically effective medical agent by a predetermined number ofdroplets of proper size from a discharge orifice into an airflow to beinhaled through a mouthpiece or the like under the effect of a bubblejet or a piezoelectric element arranged in an ejection head section(ejecting section) (see International Publication WO95/01137 andInternational Publication WO02/04043).

DISCLOSURE OF THE INVENTION

The proposed apparatus make it possible to eject droplets of uniformsize. However, since the ejection head section of the apparatus isdirectly subjected to negative pressure that is produced by theatmospheric pressure as pressure difference at the time of inhalation,liquid can leak from the orifice also at the time of inhalation. Whenliquid leaks, it is not turned into droplets of proper size and liquidis no longer ejected from the clogged orifice. Then, it is no longerpossible to eject droplets by a predetermined quantity. Additionally,the ejection head section is directly subjected to negative pressure tocurtail the service life of the ejection head section. Thus, theproposed apparatus can hardly find practical applications.

In view of the above-identified problems, it is therefore the object ofthe present invention to provide an inhaling apparatus to be used by auser to inhale a liquid medical agent from an inhalation port thereof,the apparatus comprising: a liquid medical agent ejecting section havingan ejection port for ejecting a liquid medical agent as droplets; and apressure detecting section for detecting the negative pressure producedby the atmospheric pressure as pressure difference at the time ofinhalation of the user for the purpose of controlling the ejection ofdroplets from the ejection port; the ejection port of the liquid medicalagent ejecting section being arranged at a position producing a pressuredifference smaller than the pressure difference with the atmosphericpressure as detected by the pressure detecting section at the time ofinhalation.

In another aspect of the present invention, there is provided amouthpiece to be removably fitted to an inhaling apparatus according tothe invention to form a flow path for an airflow between an inhalationport and an external air intake port, the mouthpiece comprising:pressure alleviating means arranged on the halfway of the flow path toalleviate the negative pressure of the ejecting section; a part (e.g., acommunication hole communicating with a negative pressure sensor, whichwill be described hereinafter) for receiving the pressure detectingsection to be arranged therein, the part being arranged closer to theinhalation port than the pressure alleviating means; and a part (e.g., aliquid medical agent intake port, which will be described hereinafter)for receiving the ejection port of the liquid medical agent ejectingsection to be arranged therein, the part being arranged closer to theexternal air intake port side than the pressure alleviating means.

In still another aspect of the present invention, there is provided aninhaling apparatus to be used by a user to inhale a liquid medical agentfrom an inhalation port thereof, the apparatus comprising: a flow pathfor forming an airflow by means of an inhaling action of a user, theflow path having the inhalation port at an end thereof; a liquid medicalagent ejecting section having an ejection port arranged in the flow pathto eject the liquid medical agent as droplets; and a pressure detectingsection arranged in the flow path for detecting the negative pressureproduced by the atmospheric pressure as pressure difference at the timeof an inhaling action of the user; the ejection port of the liquidmedical agent ejecting section being arranged at a position adapted toproduce a pressure difference smaller than the pressure difference withthe atmospheric pressure as detected by the pressure detecting sectionat the time of the inhaling action.

Thus, according to the present invention, since the ejection port of theliquid medical agent ejecting section is arranged at a position wherethe pressure difference with the atmospheric pressure is smaller thanthe pressure difference detected by the pressure detecting section atthe time of inhalation, the risk of liquid leakage from the ejectingsection is minimized to by turn minimize the adverse effect of leakingliquid on the service life of the ejecting section.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of an example of inhaler orinhaling apparatus according to the present invention;

FIG. 2 is a schematic perspective view of the inhaling apparatus of FIG.1 in a state where the access cover is opened;

FIG. 3 is a schematic perspective view of an example of the CRG unit;

FIG. 4 is a schematic cross sectional view of an example of mouthpiecetaken along a lateral surface thereof;

FIG. 5 is a schematic cross sectional view of the mouthpiece of FIG. 4taken along the front surface thereof;

FIG. 6 is a schematic cross sectional view of the mouthpiece of FIG. 4,illustrating the position relation with the negative pressure sensor andthe ejection head section of the CRG unit;

FIG. 7 is a schematic cross sectional view of the inhaler or inhalingapparatus of FIG. 1, showing the entire apparatus;

FIG. 8 is a graph illustrating an inhaling operation of the inhaler orinhaling apparatus of FIG. 1;

FIG. 9 is a flow chart of the overall operation of the inhaler orinhaling apparatus of FIG. 1;

FIG. 10 is a schematic cross sectional view of Embodiment 2 of thepresent invention, which is a parallel flow paths type, showing theconfiguration of the mouthpiece and its vicinity; and

FIGS. 11A and 11B are schematic cross sectional view of Embodiment 3 ofthe present invention comprising a valve, illustrating its operation.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be described. Anembodiment of inhaling apparatus or inhaler according to the inventionis designed to be carried by the user. It comprises a memory means forstoring personal information of the user, including information on themedical chart and the medical prescription of the user. It is designedto eject micro-droplets of a liquid medical agent by a predeterminedamount so as to have the user inhale the agent. The micro-droplets arehighly uniform in terms of their sizes. With this embodiment, the usercan put a mouthpiece, which has an inhalation port by way of which theuser can inhale the liquid medical agent, and an ejection head cartridge(CRG) unit to an inhaler main body. The ejection head cartridge unitincludes a tank containing the agent and is adapted to eject the agentsupplied from the tank as micro-droplets. Thus, the user can efficientlyand hygienically inhale the liquid medical agent according to theinformation provided by the prescription.

The flow path for establishing an airflow in the entire inhaler isformed only by the mouthpiece. The mouthpiece is provided on the halfwaythereof with a narrowed section that operates as a pressure alleviatingmeans. A pressure detecting section is arranged at a position closer tothe user than the narrowed section (at the side close to the inhalationport) to detect the pressure there and the ejecting section of the CRGunit is arranged at a position closer to the external air intake portthan the narrowed section. The liquid medical agent can flow out throughthe ejection port to clog the ejection port when negative pressurehigher than a predetermined level (e.g., higher than −0.3 KPa (orgreater than an absolute value of 0.3)) is applied to the ejection headsection. Then, the liquid medical agent will not be ejected properlythereafter. However, the narrowed section prevents the ejection headsection from being directly subjected to the negative pressure generatedwhen the user inhales the liquid medical agent so that micro-dropletsare continuously and smoothly ejected from the ejection port of theejection head section. In other words, the ejection port of the ejectingsection is arranged at a position where the pressure difference from theatmospheric pressure that is produced at the time of inhalation is suchthat the liquid medical agent would not be ejected naturally from theejection port by the negative pressure produced by the atmosphericpressure so that micro-droplets of the agent are ejected smoothly.Micro-droplets of the liquid medical agent may be ejected in any mode ofoperation so long as they are ejected through an orifice. For example,thermal energy, piezoelectric energy or energy produced by pressurizingliquid may be utilized to eject micro-droplets through an orifice.However, the use of an ink-jet system, which may be a bubble jet systemor a piezo jet system, is preferable. When an ink-jet system is used,liquid is supplied from a tank that is exposed to the atmosphere by thecapillary force of a nozzle so that environmental pressure needs to befound within a range that allows the negative pressure produced by thetank and the meniscus of the ejection port to be well balanced with eachother. From this point of view, the use of the arrangement of thepresent invention is very effective.

As shown in FIG. 8, an ejecting operation from the ejection port startswhen the pressure detecting section detects negative pressure of apredetermined level. However, the lowest negative pressure that thepressure detecting section detects needs to be defined appropriatelybecause the negative pressure produced in the pressure detecting sectionas a result of inhalation can vary from person to person and generallyrelates to the breathing capacity of the lungs. Considering aboutchildren and senior persons having a relatively small breathingcapacity, the cross sectional area of the narrowed section is preferablydefined to be about 10 mm² so that the negative pressure may be higherthan −0.5 Kpa (or greater than an absolute value of 0.5). Then, it ispossible for the pressure detecting section to accurately observechanges in the negative pressure produced as a result of inhalation(inhalation curve as shown in FIG. 8).

Since the flow path for establishing an airflow in the entire inhaler isformed only by the mouthpiece, the airflow section is contaminated bythe liquid medical agent only in the flow path of the mouthpiece. Inother words, the inside of the inhaler is held safe and hygienic only bywashing the mouthpiece.

The efficiency of inhalation can be improved when more liquid medicalagent is brought into the lungs of the user by changing some or all ofthe parameters (ejection speed, ejection time, etc.) relating to theejection of the liquid medical agent typically according to the inhaledquantity (in other words depending on the change of the inhalation curveas shown in FIG. 8 that is detected by the pressure detecting section).When an inhaler according to the invention is equipped with an ejectioncontrol means that is adapted to change some or all of the parametersrelating to the ejection of the liquid medical agent depending on to thechange in the flow rate for inhalation (the change in the negativepressure) as detected by the negative pressure sensor within apredetermined time period for which the user inhales the liquid medicalagent, it may additionally provided with a notification means thatoperates when the user could not inhale a predetermined quantity of theliquid medical agent within the predetermined time period so as tonotify the user that he or she needs to inhale the liquid medical agentonce again. Such an embodiment is easy to use because it minimizescumbersome operations that have to be carried out by the user. Thus,such an embodiment can be used by anyone at anywhere.

An inhaling apparatus according to the invention may alternatively beconfigured in a manner as described below.

A valve that constantly and substantially closes the flow path of anairflow except when the apparatus is operated for inhalation may be usedfor the pressure alleviating means. Then, the pressure detecting sectionis arranged at a position closer to the inhalation port than the valveand the ejection port of the ejecting section is arranged at theopposite side of the valve. As the apparatus is operated for inhalation,the valve that has been closed starts opening. Then, the negativepressure is alleviated before it gets to the ejection port of theejecting section located at the side opposite to the inhalation port ata slightly delayed timing so that the valve operates as a pressurealleviating means.

Still alternatively, the pressure detecting section and the ejectionport of the ejecting section may be so arranged as to face respectiveflow paths coming from the inhalation port. With this arrangement, oneflow path has its exit at the inhalation port, which inhalation port isformed around the exit of the flow path to show a profile similar tothat of the mouth of human being and have a part forming another flowpath. The pressure detecting section (with a communication holecommunicating with the negative pressure sensor) is arranged as facingthe another flow path.

Still alternatively, an inhaler according to the invention may beprovided with a means for monitoring the inhaled quantity, utilizing thenegative pressure sensor, (in other words, monitoring the inhalationcurve as shown in FIG. 8) and notifying the user if the inhaled quantityis appropriate or not by flashing an LED or by changing the mode ofvibration of a vibratory motor. Further, the inhaler comprises a meansfor notifying the user of the inhalation time period from the start ofinhalation and when the inhalation should be stopped. As for the meansfor notifying the inhalation time period, a means that uses thevibration of the vibratory motor can be used.

Thus, an inhaling apparatus according to the invention having any of theabove-described configurations can alleviate the physical and mentalburden imposed on the patient (user) and allow the patient to inhale the(liquid) medical agent with ease. Therefore, an inhaling apparatusaccording to the invention can accurately control the patient's actionof inhaling the medical agent according to the prescription and feed agreater amount of medical agent to the lungs than ever to improve theefficiency of inhalation so as to efficiently administer the medicalagent by changing the drive parameters relating to the ejection of theliquid medical agent according to the quantity of the medical agentinhaled by the patient.

Now, the present invention will be described in greater detail byreferring to the accompanying drawings that illustrate preferredembodiments of the invention.

Embodiment 1

FIG. 1 is a schematic perspective view showing the outer appearance ofan inhaler according to the present invention. Referring to FIG. 1,there are shown an inhaler main body 1, an access cover 2 and a frontcover 3, which constitute the housing of the inhaler. In FIG. 1,reference symbol 5 denotes a lock lever urged by a spring and having aclaw-like part at the front end thereof that engages with a projectingsection 2 a arranged at the front end of the access cover 2 in order toprevent the access cover 2 from opening in operation. As the lock leveris driven to slide downward, the access cover 2 is turned around a hingepivot (not shown) to become open by the resilience of the access coverreturning spring (not shown) that urges the access cover 2. In FIG. 1,reference symbol 101 denotes a power supply switch and reference symbol102 denotes a display LED which indicates that an ejection headcartridge (CRG) unit or a mouthpiece, which will be described in greaterdetail hereinafter, is not mounted in the housing or that the tank ofthe CRG unit is empty and no liquid medical agent is contained therein.

FIG. 2 is a schematic perspective view of the inhaler of FIG. 1 in astate where the access cover 2 is opened. As the access cover 2 isopened, the CRG unit 6 and the mouthpiece 4 that are mounted in thehousing along a CRG guide 20 are exposed. The mouthpiece 4 is locatedunder the CRG unit 6. They are mounted so as to be transversal relativeto each other. FIG. 3 is a schematic perspective view of the entire CRGunit 6. The CRG unit 6 comprises a tank 7 for containing a liquidmedical agent, a head section (ejecting section) 8 for ejecting theliquid medical agent, a part (electrically connecting section) 9 havingan electric connection surface for supplying electric power from battery10 (see FIG. 7) to cause the heater arranged in the head section 8 togenerate thermal energy and so on. The battery 10 is rechargeable andoperates as secondary cell for storing electric power in the inside ofthe inhaler in order to cause the heater to generate thermal energy. Thefront surface section of the CRG unit 6 can be opened around a hingesection 24 to allow access to the tank 7. A projection is typicallyformed on the rear surface of the front surface section so that theprojection forcibly moves into the tank 7 and slightly applies pressureto the liquid medical agent in the tank 7 to refresh the ejection portof the head section 8 at the moment that the front surface section isclosed.

FIGS. 4 and 5 are schematic cross sectional views of the mouthpiece 4.The mouthpiece 4 alone forms an airflow path and is provided at a partlocated close to its air intake port 11 with a window (liquid medicalagent intake port) 12 for taking the liquid medical agent from theejection port of the head section 8 of the CRG unit 6 into the inside ofthe mouthpiece 4. A narrowed section 4 a is formed on the halfway of themouthpiece 4 so as to gradually reduce the cross sectional area. Asshown in FIG. 6 in detail, an air hole 13 is bored at a part of the flowpath where the cross sectional area increases from that of the narrowedsection 4 a so as to make the flow path communicate with the measuringhole of a negative pressure sensor 19 for detecting the rate ofinhalation or the inhaled quantity that is the value of the integral ofthe rate of inhalation by detecting the negative pressure there. Thenegative pressure sensor 19 is arranged on a control substrate 21 (seeFIGS. 6 and 7). An expanded space 22 is arranged on the halfway of theflow path between the air hole 13 and the negative pressure sensor 19.The expanded space 22 operates as pool for storing dirt, dust, waterdrops and the liquid medical agent in order to prevent them fromentering through the air hole 13 and adhering to the surface of thenegative pressure sensor 19 so that the inhaler may not operateimproperly.

A mouthpiece exit (inhalation port) 15 is formed at the end of themouthpiece 4 opposite to the air intake port 11 so as to show a profileadapted to be held in the mouth of the user. The mouthpiece exit 15shows an elliptic cross section that matches the profile of the mouth ofhuman being. The inside of the mouthpiece 4 has a dual structure and aflow path exit 14 is formed to allow the liquid medical agent to passthrough the inside. The flow path exit 14 is so formed as to show aprofile that makes its cross sectional area gradually increase because,if the exit increases its cross sectional area suddenly, the mixed fluidof air and the liquid medical agent can be expanded abruptly to adhereto some of the teeth of the user who is holding the mouthpiece exit inhis or her mouth. Thus, the user is suggested to allow the end of theflow path exit 14 to slightly pass through his or her teeth when holdingthe mouthpiece exit 15 in the mouth. The end of the flow path exit 14may be so formed as to slightly extend outward beyond the end of themouthpiece exit 15 so that the user can allow the end of the flow pathexit 14 to pass through the teeth with ease. As shown in FIGS. 1 and 2,the airflow path of the mouthpiece 4 shows a rectangular cross sectionso that the mouthpiece 4 can be mounted in the housing with the airintake port 11 reliably directed upward.

FIG. 7 is a schematic cross sectional view of this embodiment ofinhaling apparatus, showing the entire apparatus. A control substrate 21for controlling the inhaler is arranged below the battery 10. Thecontrol substrate 21 is connected to a probe substrate 16 by way of acable or a connector (a connector 25 is used in FIG. 7), which probesubstrate 16 is arranged below the CRG unit 6. A contact probe 17 isalso arranged to connect the probe substrate 16 and the electricallyconnecting section 9 of the CRG unit 6 and electrically energize thehead section 8 of the CRG unit 6 for the purpose of emission of heat. Avibration motor 18 is arranged in contact with the control substrate 21in the space between the battery 10 and the mouthpiece 4.

Now, the operation of inhalation of this embodiment having theabove-described configuration will be described by referring to FIG. 8.

As the user starts inhalation and the negative pressure (relating to therate of inhalation or the flow rate) detected by the negative pressuresensor 19 reaches a level that allows ejection of the liquid medicalagent to take place, the inhaler starts ejecting the liquid medicalagent from the head section 8 of the CRG unit 6 under the control of thecontrol substrate 21 and the vibration motor 18 starts vibrating at thesame time to notify the user that the inhaler start ejecting the liquidmedical agent. After the end of ejection of a predetermined quantityfrom the head section 8, the vibration motor 18 keeps on vibrating for asupplementary inhalation time that is determined on the basis of therate of inhalation and the continuous inhalation time as computed fromthe negative pressure value of the negative pressure sensor 19 for thepurpose of encouraging the user to inhale a quantity for supplementaryinhalation and so that the ejected liquid medical agent may completelyreach the lungs. As the vibration motor 18 stops vibrating, the user, orthe patient, stops inhaling the liquid medical agent. With thisarrangement, the process of ejecting the liquid medical agent and thatof inhalation are interlocked with each other so that the liquid medicalagent is reliably fed into the lungs to avoid a failure of insufficientinhalation.

As the result of the inhaling action of the user, air is fed into themouthpiece 4 from the air intake port 11 to produce a mixed fluid of airand the liquid medical agent ejected from the ejection port arranged inthe head section 8 of the CRG unit 6. The mixed fluid is then led to themouthpiece exit 15 having a profile adapted to be held in the mouth ofthe user. The mouthpiece exit 15 is adapted to prevent the mixed fluidfrom leaking through the lateral ends of the mouth, minimizing the wasteof the mixed fluid, and cause the mixed fluid to hardly collide with theobstacles in the mouth such as teeth so that the liquid medical agentmay be efficiently inhaled into the body of the user.

This embodiment is provided with the vibration motor 18 because the usermay not want to be known about his or her use of the inhaler andvibrations may be more preferable than sounds to the user asnotification means. Thus, with this arrangement, the embodiment can beused by anyone at anywhere.

An example of overall operation of the inhaling apparatus will bedescribed below by referring to the flow chart of FIG. 9. As the powersupply switch 101 is turned on, the open or closed state of the accesscover 2 is detected (S801). If the access cover 2 is open, the user iswarned about it typically by means of the display LED 102. If it isclosed, it is then detected if a CRG unit 6 is mounted or not (S802). Inthe example, if a CRG unit 6 is not mounted, a Bluetooth communicationis started (S803) to exchange data with the user, including data on thequantity to be administered to the user (S804). The operation ends whenthe communication is completed (S805). This mode of operation may beutilized mainly by the doctor of the user.

If, on the other hand, a CRG unit 6 is mounted, the operation proceedsin a manner as described below. This mode of operation may be utilizedmainly by the patient, or the user. As the user starts inhalation (S806)and the inhalation is detected, negative pressure is detected by thenegative pressure sensor 19 when it reaches a predetermined level(S807). Then, the ejection head section 8 starts ejecting the liquidmedical agent (S808). If it is not detected that negative pressurereaches a predetermined level, a warning for prompting the user toinhale harder may be issued.

The liquid medical agent is ejected for a predetermined time periodafter the start of ejection so that a predetermined quantity of theliquid medical agent may be ejected. The quantity is determined on thebasis of the data read in by the inhaling apparatus. Subsequently, thenegative pressure sensor 19 monitors the change with time of negativepressure due to inhalation and the inhaling apparatus detects if thepredetermined quantity has been inhaled or not on the basis of the valueof the integral of the change with time (S809). The time for startingthe integral may be selected appropriately. Since the integrated valuerelates to the inhaled quantity of the mixed fluid of air and the liquidmedical agent, it corresponds to detecting if the liquid medical agenthas been inhaled by the predetermined quantity. The operation ends whenthe liquid medical agent has been inhaled by the predetermined quantity.Then, the vibration motor 18 stops vibrating. If it is not detected thatthe liquid medical agent has been inhaled by the predetermined quantityafter the elapse of a predetermined time period, a warning is issued tothe user typically by means of a change in the mode of vibration of thevibration motor 18 in order to prompt the user to inhale the liquidmedical agent again (S806). In such a case, the quantity short of thequantity to be inhaled is computed (S810) and the quantity of the liquidmedical agent to be ejected from the ejection head section 8, theinhalation time period (or the vibration time period of the vibrationmotor 18) and other necessary values are computationally determinedaccordingly.

Since the ejection port of the liquid medical agent ejecting section isarranged reliably at a position where the pressure difference with theatmospheric pressure is smaller than the pressure difference detected bythe pressure detecting section at the time of inhalation in the abovedescribed embodiment, the risk of liquid leakage from the ejectingsection is minimized to by turn minimize the adverse effect of leakingliquid on the service life of the ejecting section. Furthermore, theliquid medical agent is reliably and efficiently administered to theuser by a predetermined quantity by way of a simple operation.

Embodiment 2

FIG. 10 is a schematic cross sectional view of Embodiment 2 of thepresent invention, which differs from Embodiment 1 only in terms of theconfiguration of the flow path to the pressure detecting section (thecommunication hole 13 communicating with the negative pressure sensor19). In Embodiment 2, the communication hole 13 is arranged to theoutside of the flow path exit 14 of the mouthpiece exit 15 located atthe front end of the mouthpiece 4. With this arrangement, a negativepressure detecting flow path led to the negative pressure sensor 19 iscompletely separated from and arranged in parallel with the airflow pathof the mouthpiece 4. When the mouthpiece 4 is mounted in the apparatusfrom the upper and front surface thereof, the mounting direction agreeswith the direction in which the communication hole 13 comes tightlyclose to the negative pressure detecting flow path led to the negativepressure sensor 19. Thus, this arrangement is advantageous forpreventing air from leaking. Then, negative pressure is reliablydetected. Additionally, since the negative pressure detecting flow pathled to the negative pressure sensor 19 and the liquid medical agent flowpath are completely separated from each other, the negative pressuredetecting flow path is minimally contaminated by the liquid medicalagent to ensure a highly accurate detection of negative pressure.Otherwise, Embodiment 2 is identical with Embodiment 1.

Embodiment 3

FIG. 11A and 11B show Embodiment 3 comprising a pressure alleviatingmeans that is different from the narrowed flow path of Embodiment 1. Avalve 30 having a size substantially same as the cross sectional area ofthe flow path of the mouthpiece 4 is rotatably arranged between thecommunication hole 13 led to the negative pressure sensor 19 and theliquid medical agent intake port 12 receiving the ejection head section8 in the flow path of the mouthpiece 4. The valve 30 is constantly heldto state where it substantially closes the flow path as it is made toabut a valve stopper 31 as illustrated in FIG. 11A. The valve 30 isopened as shown in FIG. 11B when the user starts an inhaling operation.While relatively strong negative pressure is generated in the flow pathspace at the side of the negative pressure sensor 19 at this time, suchstrong negative pressure is not generated in the flow path space at theside of the ejection head section 8. Thus, the net results will be sameas those of Embodiment 1. Otherwise, Embodiment 3 is identical withEmbodiment 1.

The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention, the following claims are made.

This application claims priority from Japanese Patent Application No.2004-225510 filed on Aug. 2, 2004, which is hereby incorporated byreference herein.

1-11. (canceled)
 12. An inhaling apparatus to be used by a user toinhale a liquid medical agent from an inhalation port thereof, theapparatus comprising: a flow path for forming an airflow by means of aninhaling action of a user, said flow path having said inhalation port ata first end thereof and an air intake port at a second end thereof; apressure detecting section for detecting a negative pressure produced insaid flow path by the inhaling action of the user, said pressuredetecting section communicating with said flow path via a communicationhole; and a liquid medical agent ejecting section arranged in said flowpath, said ejecting section having an ejection port and anelectrothermal or piezoelectric element for ejecting the liquid medicalagent in response to the negative pressure detected by said pressuredetecting section, characterized in that a pressure alleviating means isprovided in said flow path at a position closer to the inhalation portthan said ejecting section, for alleviating the negative pressureproduced at said ejecting section, and the communication hole isarranged in said flow path at the pressure alleviating means or at aposition closer to the inhalation port than said pressure alleviatingmeans.
 13. The apparatus according to claim 12, wherein said pressurealleviating means is a narrowed section having a smaller cross sectionalarea in said flow path forming an airflow.
 14. The apparatus accordingto claim 12, wherein said pressure alleviating means is a valve whichopens as the apparatus is operated for inhalation.
 15. An inhalingapparatus to be used by a user to inhale a liquid medical agent from aninhalation port thereof, the apparatus comprising: a flow path forforming an airflow by means of an inhaling action of a user, said flowpath having said inhalation port at a first end thereof and an airintake port at a second end thereof; and a liquid medical agent ejectingsection arranged in said flow path, said ejecting section having anejection port and an electrothermal or piezoelectric element forejecting the liquid medical agent, characterized in that a pressurealleviating means is provided in said flow path at a position closer tosaid inhalation port than said ejecting section, for alleviating thenegative pressure produced at said ejecting section.
 16. The inhalingapparatus according to claim 15, further comprising a pressure detectingsection for detecting a negative pressure produced in said flow path bythe inhaling action of the user, said pressure detecting section beingarranged outside a flow path exit in said inhalation port.